How it's made: Methods to Improve Weather Radar Data

As part of the How It’s Made series, we’re going under the hood of weather forecasting in our 20-part series. Over the coming weeks, we’ll be exploring the Five Categories that create an accurate, reliable forecast. Each article in the series is a stand-alone story, but together they explain precisely how the Five Categories tie together to take a weather forecast from good to great.

Following on from How the Experts Enhance Weather Station Data, we’re continuing our exploration of Category One: Weather Observations, with this post on weather radar.

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Weather radar uses radio waves to locate precipitation. It calculates the distance, the direction, and elevation of precipitation. Additionally, some radars provide the type of precipitation (e.g. rain, snow or hail). Currently, radar data is primarily available from national met offices, which operate radar networks.

During the Second World War, radar operators noticed a background echo showing up on their displays. Further investigation showed it was the weather causing this interference.

Since this discovery, meteorologists use weather radar to predict oncoming precipitation and weather patterns more accurately than previously possible.

What data is available from radar?

“Good radar data is an essential source for real time and short term weather forecast”
- Floris Bijlsma, Senior Meteorological Researcher

Radar data is primarily available from national met offices, which operate radar networks. Some companies offer to install local radars, but these have limited coverage. The main types of data available are:

● Basic radar: This is a precipitation image at a semi-constant height of 1km above ground level, often created using data from multiple radar sites.

● Volume data: This is 3D data showing radar reflectivity. In other words, it's the items the radio waves have encountered.

● Precipitation type: This is a precipitation image, showing the type and intensity of the precipitation.

● Derived products: These include hail indicators, cloud top height, or cumulative radar.

How do weather experts improve the data to create a forecast?

Weather experts will typically take basic radar data, such as location and intensity, and enhance it, using their expertise and insights to create a unique value set of data points. For example, they use the movement of precipitation from radar to create a movement field. This information is then applied to real-time data to help map the possible rainfall in the next three hours. Additionally, they’ll bring together data from multiple sources to provide insight over a large area, such as a whole country or even the whole of Europe.

The Five Methods to Improve Weather Data

#1 Merged radar data: This improvement combines radar reflectivity images from multiple radar sources to provide insights into a broad geographical area, for example, a country or even the whole of Europe. This improvement is beneficial for media companies, which use radar images to visualize the weather forecast in their broadcasts.

#2 Decluttered radar data: Weather radar can pick up false signals caused, for example, by wind turbines. This improvement corrects the data to reduce the number of false precipitation signals caused by turbines and other signal or echo anomalies.

#3 Expected radar: This improvement uses the data to create a movement field of the precipitation, which is applied to real-time data to extrapolate the expected precipitation for the next three hours. This type of insight forecasting is essential for any business operations affected by precipitation.

#4 Precipitation type radar data: This combines conventional radar data with probability forecasts of snow/hail/rain, taken from MOS (Model Output Statistics) forecast, to provide a precipitation type forecast. This type of weather data is particularly important for managing winter road conditions, as well as rail and aircraft operations.

#5 Cumulative radar: This combines multiple radar images to calculate the estimated precipitation amount over 1-, 3-, 6-, and 24-hour periods. In some locations, this can also be calibrated with ground observations.

Weather radar helps minimize the impact of precipitation on business

Weather radar data is particularly important for monitoring the weather and identifying situations where the weather can be a risk, including severe weather warnings and dangerous road conditions.

Knowing when precipitation is going to fall, the type of precipitation and how likely it is to last can help businesses to manage their operations more effectively and minimize the impact the weather has on profitability.

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